5720 Organometallics, Vol. 29, No. 21, 2010
Lichtenberg et al.
[Al(η1-C3H5)2(C5H5N)2]þ[BPh4]-: 1H NMR (400.1 MHz,
immediately; X = Br: after 30 s; X = Cl: 30 min) from the
colorless solution.
3
THF-d8): δ 1.58 (br d, JHH = 8.5 Hz, 4H, HR), 4.59 (br d,
3JHH = 10.0 Hz, 2H, Hγ), 4.67 (br d, 3JHH = 16.9 Hz, 2H, Hδ),
5.93 (br ddt, 3JHH = 8.5 Hz, 3JHH = 10.0 Hz, 3JHH = 16.9 Hz,
In all nine cases, the course of the reaction was monitored by
1H and 13C NMR spectroscopic measurements, and the forma-
tion of the desired product, 1,5-hexadiene, was observed.35
Competition Experiment of 3 with an Equimolar Mixture of
Allyl Iodide and Allyl Bromide. Allyl iodide (39 mg, 232 μmol)
and allyl bromide (28 mg, 231 μmol) were dissolved in THF-d8
(600 μL). The resulting colorless solution was analyzed by
2H, Hβ), 6.72 (br t, 3JHH = 7.2 Hz, 4H, p-Ph), 6.85 (br t, 3JHH
=
7.4 Hz, 8H, o-Ph), 7.28-7.31 (m, 8H, m-Ph), 7.32-7.34 (m, 4H,
m-py), 7.75-7.79 (m, 2H, p-py), 8.37-8.39 (m, 4H, o-py) ppm.
THF was also detected.
Reactions of 1, 2, and 3 with Benzophenone. The aluminum
compound (1: 27 mg, 121 μmol, 2: 19 mg, 33 μmol, 3: 13 mg, 56
μmol) was dissolved in THF-d8 (300 μL). A solution of benzophe-
none (in the case of 1: 66 mg, 362 μmol; in the case of 2: 12 mg, 66
μmol; in the case of 3: 41 mg, 226 μmol) in THF-d8 (300 μL) was
slowly added. In all three cases colorless solutions were obtained.
1: After a reaction time of e10 min a quantitative conversion to
1
means of H NMR spectroscopy. Upon addition of 3 (27 mg,
117 μmol), a colorless solid precipitated immediately. After
1
30 min H NMR spectroscopic measurements confirmed the
formation of 1,5-hexadiene (117 μmol).35 These analyses also
showed the consumption of allyl iodide to be 3.2 times higher
than the consumption of allyl bromide.
1
the insertion product 4 was observed. H NMR (400.1 MHz,
Reactions of 1, 2, and 3 with X2 (X = I, Br). X = I, one
equivalent of I2 per allyl substituent: The aluminum compound
(1: 28 mg, 125 μmol; 2: 20 mg, 35 μmol; 3: 8 mg, 35 μmol) was
dissolved in THF-d8 (600 μL). Iodine (in the case of 1: 97 mg, 382
μmol; in the case of 2: 18 mg, 71 μmol; in the case of 3: 35 mg, 138
μmol) was added to the colorless solution. After 2 min a color-
less solution (in the case of 1 and 2) or a suspension of a colorless
solid in a colorless solution (in the case of 3) was obtained.
Quantitative amounts of allyl iodide were formed in each case
according to NMR spectroscopic analyses.36
X = I, 0.50 equivalent of I2 per allyl substituent: The
aluminum compound (1: 28 mg, 125 μmol; 2: 20 mg, 35 μmol;
3: 8 mg, 35 μmol) was dissolved in THF-d8 (600 μL). I2 (in the
case of 1: 97 mg, 382 μmol; in the case of 2: 18 mg, 71 μmol; in the
case of 3: 35 mg, 138 μmol) was added to the colorless solution.
After 2 min a colorless solution (in the case of 1 and 2) or a
suspension of a colorless solid in a colorless solution (in the case
of 3) was obtained. The reaction mixtures were analyzed by
means of 1H and 13C NMR spectroscopy. In all three cases the
iodine was quantitatively converted and the appropriate
amount of allyl iodide was detected after a reaction time of
e20 min.36 The in situ generated aluminum allyl iodides and the
allyl iodide were allowed to further react, and the course of these
reactions was monitored by means of 1H and 13C NMR
spectroscopy.
1: no 1,5-hexadiene was detected over a period of more than 6
days. 2: After 18 days a conversion of >95% of the in situ
generated allyl iodide was observed with a selectivity of 80%
toward 1,5-hexadiene.35 3: After 18 days a conversion of 39% of
the in situ generated allyl iodide was observed with a selectivity
of 67% toward 1,5-hexadiene.35
X = Br, 0.50 equivalent of Br2 per allyl substituent: The
aluminum compound (1: 33 mg, 148 μmol; 2: 36 mg, 63 μmol; 3:
25 mg, 109 μmol) was dissolved in THF-d8 (600 μL). Bromine (in
the case of 1: 36 mg, 225 μmol; in the case of 2: 10 mg, 63 μmol; in
the case of 3: 35 mg, 219 μmol) was added to the colorless
solution. After 2 min a colorless solution (in the case of 1 and 2)
or a suspension of a colorless solid in a colorless solution (in the
case of 3) was obtained. In all three reactions full conversion of
the starting materials was observed within less than 1 h and the
reaction mixtures were analyzed by means of 1H and 13C NMR
spectroscopy. 1: 1,5-Hexadiene was formed as the main product
with 39% selectivity;35 1,2,3-tribromopropane was also detected
next to unidentified side products.37 2: 1,5-Hexadiene was
THF-d8): δ 1.74-1.78 (m, 4H, β-THF), 3.06 (br d, 3JHH =6.7Hz,
6H, HR), 3.60-3.63 (m, 4H, R-THF), 4.78 (br dd 4JHH = 1.5 Hz,
3JHH = 10.3 Hz, 3H, Hγ), 4.85 (br dd 4JHH = 1.7 Hz, 3JHH = 17.3
3
3
Hz, 3H, Hδ), 5.75 (br ddt, JHH = 6.7 Hz, JHH = 10.3 Hz,
3JHH = 17.3 Hz, 3H, Hβ), 7.09 (br t, 3JHH = 7.2 Hz, 6H, p-Ph),
7.17 (br t, 3JHH = 7.4 Hz, 12H, m/o-Ph), 7.37 (br d, 3JHH = 7.4
Hz, 12H, m/o-Ph) ppm. 13C NMR (100.6 MHz, THF-d8): δ 26.38
(s, β-THF), 48.69 (s, C1), 68.33 (s, R-THF), 79.71 (s, C(O[Al])-
(C3H5)Ph2), 116.24 (s, C3), 126.49 (s, p-Ph), 128.10 (s, m/o-Ph),
128.24 (s, m/o-Ph), 137.53 (s, C2), 151.28 (s, ipso-Ph) ppm.
2: After a reaction time of e10 min a quantitative conversion
of the reactants into 90% of the insertion product 5 was
observed. 1H NMR (400.1 MHz, THF-d8): δ 1.75-1.78 (m,
3
8H, β-THF), 2.96 (br d, JHH = 6.7 Hz, 4H, HR), 3.60-3.63
(m, 8H, R-THF), 4.91 (dm 3JHH = 10.3 Hz, 2H, Hγ), 4.95 (dm
=
3
3
3JHH = 17.2 Hz, 2H, Hδ), 5.49 (ddt, JHH = 6.7 Hz, JHH
10.3 Hz, 3JHH = 17.2 Hz, 2H, Hβ), 6.76 (br t, 3JHH = 7.2 Hz,
4H, B(p-Ph)), 6.89 (br t, JHH = 7.4 Hz, 8H, B(o-Ph)), 7.18-
3
7.20 (m, 8H, C(m-Ph)), 7.21-7.24 (m, 4H, C(m-Ph)), 7.25-7.30
(m, 8H, C(o-Ph)) 7.30-7.33 (m, 8H, B(m-Ph)) ppm. 13C NMR
(100.6 MHz, THF-d8): δ 26.29 (s, β-THF), 48.14 (s, C1), 68.20
(s, R-THF), 80.34 (s, C(O[Al])(C3H5)Ph2), 118.08 (s, C3), 121.98
(s, B(p-Ph)), 125.84 (s, B(o-Ph)), 127.35 (C(m/o-Ph)), 127.78
(s, C(p-Ph)), 128.95 (s, C(m/o-Ph)), 135.63 (s, C2), 137.03(s,
B(m-Ph)), 149.08 (s, C(ipso-Ph)) 165.03 (s, B(ipso-Ph)) ppm.
3: After a reaction time of 10 min a conversion of only 3% was
observed. After 9 h a conversion of 99% to the insertion product
6 was observed. 1H NMR (400.1 MHz, THF-d8): δ 3.07 (d,
3
3JHH = 6.8 Hz, 8H, HR), 4.51 (dm JHH = 10.3 Hz, 4H, Hγ),
4.62 (dm 3JHH = 17.2 Hz, 4H, Hδ), 6.85 (ddt, 3JHH = 6.8 Hz,
3JHH = 10.3 Hz, 3JHH = 17.2 Hz, 4H, Hβ), 6.91-6.95 (m, 8H,
p-Ph), 6.97-7.00 (m, 16H, m/o-Ph), 7.40-7.42 (m, 16H, m/o-Ph)
ppm. 13C NMR (100.6 MHz, THF-d8): δ 49.47 (s, C1), 79.70 (s,
C(O[Al])(C3H5)Ph2), 114.02 (s, C3), 125.19 (s, p-Ph), 127.36 (s,
m/o-Ph), 129.18 (s, m/o-Ph), 140.17 (s, C2), 153.09 (s, ipso-Ph) ppm.
Reactions of 1, 2, and 3 with C3H5X (X = I, Br, Cl). 1: 1 (22 mg,
100 μmol) was dissolved in THF-d8 (600 μL), and CH2CHCH2X
(X = I: 51 mg, 304 μmol, X = Br: 37 mg, 305 μmol, X = Cl:
23 mg, 301 μmol) was added. A colorless solution was
obtained.
2: 2 (51 mg, 89 μmol) was dissolved in THF-d8 (600 μL), and
CH2CHCH2X (X = I: 30 mg, 179 μmol, X = Br: 21 mg, 174
μmol, X = Cl: 14 mg, 183 μmol) was added. A colorless solution
was obtained.
3: 3 (19 mg, 82 μmol) was dissolved in THF-d8 (600 μL), and
CH2CHCH2X (X = I: 55 mg, 327 μmol, X = Br: 40 mg, 331
μmol, X = Cl: 25 mg, 327 μmol) was added. Upon addition
of the allyl halide, a colorless solid began to precipitate (X = I:
(36) Analytical data for allyliodide: 1H NMR (400.1 MHz, THF-d8):
δ 3.90 (dm, 3JHH = 7.8 Hz, 1H, HR), 4.91 (dm, 3JHH = 9.8 Hz, 1H, Hγ),
=
5.22 (dm, 3JHH = 16.7 Hz, 1H, Hδ), 6.06 (br ddt, 3JHH = 7.8 Hz, 3JHH
9.8 Hz, 3JHH = 16.7 Hz, 1H, Hβ) ppm. 13C NMR (100.6 MHz, THF-d8):
δ 5.60 (s, C1), 117.71 (s, C3), 137.24 (s, C2) ppm.
(37) Analytical data for 1,2,3-tribromopropane: 1H NMR (400.1
MHz, THF-d8): δ 3.88 (br dd, 3JHH = 6.7 Hz, 2/4JHH = 11.1 Hz, 2H,
(35) Analytical data for 1,5-hexadiene: 1H NMR (400.1 MHz, THF-
d8): δ 2.12 (br d, 3JHH = 2.9 Hz, 2H, Haliph), 2.13 (br d, 3JHH = 2.9 Hz,
2H, Haliph), 4.92 (dm, 3JHH = 10.2 Hz, 2H, Hγ), 4.99 (dm, 3JHH = 17.0
Hz, 2H, Hδ), 5.75-5.85 (m, 2H, Hβ) ppm. 13C NMR (100.6 MHz, THF-
d8): δ 34.09 (s, C1), 115.00 (s, C3), 138.93 (s, C2) ppm.
3
2/4
C(H1)2Br), 3.99 (br dd, JHH = 4.5 Hz,
J
J
HH
= 11.1 Hz, 2H,
= 6.7 Hz, 1H,
HH
3
2/4
C(H2)2Br), 4.56 (br tt, JHH = 4.5 Hz,
CBrH) ppm. 13C NMR (100.6 MHz, THF-d8): δ 36.07 (s, CH2Br),
50.07 (s, CHBr) ppm.